Photo Illustration by Elizabeth Brockway/The Daily Beast

The numbers are in on California’s tough new vaccination law, and they reveal a disturbing phenomenon.

In June 2015, the state enacted Senate Bill 277, mandating that at the beginning of the next academic year, all students had to be vaccinated, including those in private, charter, and parochial schools. It was one of the most restrictive immunization bills in history, and a response to a measles epidemic that started in Southern California at the end of 2014 and eventually spread into 25 states and two Canadian provinces, infecting hundreds of people, mostly children.

Before SB277, California, like many states, had allowed parents to exempt themselves from vaccines. All 50 states permit medical exemptions; 47 have religious exemptions. And, before the passage of SB277, 18 states had philosophical exemptions. SB277 eliminated California’s philosophical exemption. Because California never had a religious exemption, only medical exemptions remained. With SB277, California became the third state to allow only medical exemptions (West Virginia and Mississippi are the other two).

One year after SB277 went into effect, the results are in.

First: the good news. During the past year, kindergarten immunization rates increased to 95.6 percent from 92.8 percent. When compared to two years earlier, immunization rates were up 5.2 percent. Indeed, current immunization rates in California are the highest they’ve been since 2001.

One possibility is that parents of children with true medical exemptions had previously claimed a philosophical exemption, which was obtained by simply filling out a form—much easier than getting a doctor’s letter. With the new bill, however, these parents were forced to do something they probably should have done in the first place.

Another possibility is that more children actually did require medical exemptions, which are given for several reasons. For example, children who are receiving chemotherapy for cancer or immune suppressive therapy for chronic diseases or steroids for asthma cannot receive live, weakened viral vaccines like the measles-mumps-rubella (MMR) or chickenpox vaccines. Also, children who are allergic to vaccine components, most notably gelatin or latex, cannot receive certain vaccines. But why the dramatic increase? Have children in California suddenly become more immune suppressed or allergic? Unlikely.

The most likely explanation can be found by taking a closer look at where these medical exemptions are clustered and one unusual resource that became available after the passage of SB277.

Typically, about 0.5 percent of children require a medical exemption. Indeed, the 2,850 medical exemptions requested represent 0.5 percent of California’s kindergarten population. But according to the Los Angeles Times, in 58 schools, more than 10 percent of kindergarteners chose medical exemptions; at seven schools, more than 20 percent did. Many of these exemptions occurred in Los Angeles, San Diego, and Orange counties: the same counties that produced the 2014-2015 measles epidemic.

The unusual resource? After SB277 passed, anti-vaccine websites appeared across the state coaching parents on how to request medical exemptions; many of these websites included a list of doctors sympathetic to parents who felt they were being unfairly coerced into vaccinating their children—doctors who, by requiring an office visit, were essentially selling a medical exemption. “It would be very unfortunate if there were physicians who’ve shirked their professionalism, and basically are trying to monetize their professional license by putting children at risk and betraying public health,” said Richard Pan (D-Sacramento), a physician who co-authored SB277.

Given this most recent development, it would take a counsel of the gods to determine which aspect of the anti-vaccine movement is most upsetting: parents choosing to put their children in harm’s way unnecessarily; state governments, through philosophical and religious exemptions, allowing them to do it; or doctors, in some misguided sympathy for freedom of choice, writing bogus medical exemptions for a price. At the very least, public health officials and licensing boards in California need to take a closer look at the reasons behind the dramatic increase in medical exemptions. And if they find that these exemptions have no basis in fact, doctors should be held accountable for their fraudulent behavior.